This topic describes the syntax, description, parameters, and return values of logical functions. This topic also provides examples of these functions.

and

The following table describes the details about this function.
Item Description
Syntax and(arg, ...)
Benefit
  • Executes the AND logical operator.
  • Short-circuit evaluation is supported. When a value evaluates to false, the values that follow this value are not evaluated.
Parameter The value that you want to check. You can specify one or more values. Data type: any type.
Return value Returns true if all values evaluate to true and returns false if a value evaluates to false.
Example 
if and($arg_mode, eq($arg_mode, 'set_header')) {
    add_rsp_header('USER-DEFINED-1','path1')
}
  • a. If the request includes the mode parameter and the value of the mode parameter is set_header, set the USER-DEFINED-1 response header.
  • b. If the request does not include the mode parameter, the short-circuit evaluation takes effect and the eq comparison operator is not executed. The response header USER-DEFINED-1 will not be set because the and() function returns a value of false.

or

The following table describes the details about this function.
Item Description
Syntax or(arg, ...)
Description
  • Executes the OR logical operator.
  • Short-circuit evaluation is supported. When a value evaluates to true, the values that follow this value are not evaluated.
Parameter The value that you want to check. You can specify one or more values. Data type: any type.
Return value Returns true if a value evaluates to true and returns false if all values evaluate to false.
Example 
if and($http_from, or(eq($http_from, 'wap'), eq($http_from, 'comos'))) {
    rewrite(concat('http://example.com.cn/zt_d/we2015/', $http_from), 'enhance_redirect')
}
  • a. If the request includes the From header and its value is wap or comos, the HTTP 302 status code is returned and the request is redirected to http://example.com.cn/zt_d/we2015/[wap|comos].
  • b. If the request includes the From header and its value is wap, the short-circuit evaluation takes effect and the comos value is ignored. The or() function returns a value of true.

not

The following table describes the details about this function.
Item Description
Syntax not(arg)
Description Executes the NOT logical operator. The values of undef and false evaluate to false, and other values evaluate to true.
Parameter The value that you want to check. You can specify only one value. Data type: any type.
Return value
  • true
  • false
Example 
if not($arg_key) {
    exit(403)
}
if not($cookie_user) {
    exit(403, 'not cookie user')
}
if not(0) {
    exit(403)
}
if not(false) {
    exit(403)
}
  • If a request does not include the key parameter, the request is denied and the HTTP 403 status code is returned.
  • If a request does not include cookie_user, the request is denied. The HTTP 403 status code and the response body "not cookie user" are returned.
  • The not(0) function returns a value of false.
  • The not(false) function returns a value of true.

eq

The following table describes the details about this function.
Item Description
Syntax eq(arg1, arg2)
Description Compares whether two values are equal.
Parameter
  • arg1: the first value to compare. Data type: any type.
  • arg2: the second value to compare. Data type: same as the arg1 parameter.
Return value Returns true if the two values are equal and returns false if they are not equal.
Example 
key1 = 'value1'
key2 = 'value2'
if and($arg_k1, $arg_k2, eq(key1, $arg_k1), ne(key2, $arg_k2)) {
    say('match condition')
}
  • a. If the request includes both the k1 and k2 parameters, the comparison operations are performed.
  • b. If the request does not include the k1 or k2 parameter, the short-circuit evaluation takes effect and the comparison operations are not performed.
  • eq: c. eq: whether the value of the k1 parameter is equal to value1.
  • ne: d. ne: whether the value of the k2 parameter is not equal to value2.
  • e. The response that contains the response body "match condition" is returned only if the following conditions are met: the request includes both the k1 and k2 parameters, the value of the k1 parameter is equal to value1, and the value of the k2 parameter is not equal to value2.

ne

The following table describes the details about this function.
Item Description
Syntax ne(arg1, arg2)
Description Compares whether two values are not equal.
Parameter
  • arg1: the first value to compare. Data type: any type.
  • arg2: the second value to compare. Data type: same as the arg1 parameter.
Return value Returns true if the two values are not equal and returns false if they are equal.
Example 
key1 = 'value1'
key2 = 'value2'
if and($arg_k1, $arg_k2, eq(key1, $arg_k1), ne(key2, $arg_k2)) {
    say('match condition')
}
  • a. If the request includes both the k1 and k2 parameters, the comparison operations are performed.
  • b. If the request does not include the k1 or k2 parameter, the short-circuit evaluation takes effect and the comparison operations are not performed.
  • eq: c. eq: whether the value of the k1 parameter is equal to value1.
  • ne: d. ne: whether the value of the k2 parameter is not equal to value2.
  • e. The response that contains the response body "match condition" is returned only if the following conditions are met: the request includes both the k1 and k2 parameters, the value of the k1 parameter is equal to value1, and the value of the k2 parameter is not equal to value2.

null

The following table describes the details about this function.
Item Description
Syntax null(v)
Benefit Checks whether a data type is specified for EdgeScript (ES).
Filed v: the parameter to pass. Data type: array, dictionary, or string. A value of false is returned for other data types.
Return value Data type: Boolean.
  • A value of true is returned if the value of v is an array or a dictionary.
  • A value of true is returned if the value of v is an empty string.
  • A value of false is returned if v is set to other data types.
Examples 
d = []
say(null(d))
set(d, 1, 'v1')
say(null(d))
say(tostring(null('x')))
say(tostring(null('')))
Output:
true
false
false
true